Most modern consumer and commercial appliances utilize some form of electronic or electromechanical control of the various operating cycles thereof. In, for example, consumer and commercial washing machines and dish washers, such controls enable the use of solenoid controlled water valves to begin and end the various fill and rinse cycles typical for such appliances.
While the particular controller for such appliances is typically housed in a somewhat protected area of the appliance, or utilizes some form of conformal coating to protect the control circuitry from short circuits that may otherwise be caused from water and/or liquid detergents that may come into contact therewith, the solenoid controlled water valves are typically installed in much harsher environments wherein the likelihood of water, suds, liquid detergents, and other contaminants caused by operation of the appliance and or cleaning by the operator is substantially greater. Unfortunately, the sealing of such wire terminated components has proven extremely difficult to achieve in such environments.
Indeed, in appliances such as laundry and dish washers, the event of over flow or leakage is quite common, and it is not unusual for a homeowner to attempt to clean the appliance using conductive acidic or detergent cleaners. Such low dielectric fluids would have a shorting effect on high power connections such as motors and/or valve components, if located in the path of such fluid leaks. Electrical controls are generally located high in the appliance and protected by enclosures. However, other components that are powered by leaded wires are prone to fluids wicking down the leads to the bare or unsealed terminals and junctions. Vibration, inherent in such machines or appliances, adds another degree of concern. When the wire lead is allowed to move and flex, traditional attempts to seal usually fail.
In the past, manufactures have tried various expensive and laborious methods, such as topical adhesives, sealants, ultrasonic methods, etching, etc., to provide a water tight seal. Unfortunately, many such wire terminated components such as the solenoid controlled water valves discussed above utilize flexible wires know as flying leads that contain a large amount of plasticizer and lubricants in the wire coating insulation. Such plasticizers and lubricants prevent good adhesion of sealants and adhesives to the joint. As such, water, detergents, and conductive cleaning fluids to which these components are subjected often eventually results in short circuits.
Some manufactures have attempted to overcome this problem by assembling the wire terminated components, i.e. attaching the flexible wire leads to the electrical terminals of the solenoid, and then overmolding the assembly to encapsulate the solenoid, electrical terminals, and a portion of the flexible wires attached to the solenoid terminals. Unfortunately, overmolding materials that provide good adhesion to the solenoid coils do not provide good adhesion to the insulation on the wires and vice versa. Such over-molded assemblies must rely on the minimal adhesion of the dissimilar plastics to seal the joints. This attempt, particularly when used with flexible wire, proves ineffective to low dielectric solutions that can wick down into the joint between the wire insulation and the plastic over-molded material. As a result, dielectric breakdown also often eventually occurs when such components are subjected to continuous or continual exposure to conductive fluids. Such joints do not bond in a hermetic “water tight” type seal.
There is a need, therefore, for wire terminated electrical components, such as solenoid controlled water valves, that can make use of a low cost sealing technique that will prevent or substantially reduce the occurrence of short circuits caused by continual exposure to conductive fluids. Embodiments of the present invention provide a system and method for achieving such results.